Keep showing invalid input number and set NaN on the model

When a dialog (form) is validated and show the error message from the browser,
the input number must be visible.
Also we should not store on the model invalid values to get error on client
side instead of the server side.

issue8487
review255661002

src/view/form.js

@@ -1591,8 +1591,10 @@ function eval_pyson(value){
         input.attr('lang', Sao.i18n.getlang());
 
         input.hide().on('focusout', function() {
-            input.hide();
-            input_text.show();
+            if (input[0].checkValidity()) {
+                input.hide();
+                input_text.show();
+            }
         });
         input_text.on('focusin', function() {
             if (!input.prop('readonly')) {
@@ -1626,7 +1628,11 @@ function eval_pyson(value){
                 this.record, this.get_value(), undefined, this.factor);
         },
         get_value: function() {
-            return this.input.val();
+            if (this.input[0].checkValidity()) {
+                return this.input.val();
+            } else {
+                return NaN;
+            }
         },
         get_client_value: function() {
             var value = '';